Despite repeated pummelings — four more losses Tuesday night, including a blowout in Pennsylvania — Bernie Sanders still can't find the high road on his mental GPS. He's still steamed that Democrats have the temerity to run Democrats-only primaries (he's not even a Democrat), says he's gonna win in irrelevant West Virginia on May 10 and continue to battle at the convention to the bitter end.

Perhaps, if Bernie is at all interested in losing with grace and class, in uniting with his victorious foe for the most existential crusade of our era — preventing an unhinged racist demagogue from owning the nuclear codes — he will take a moment to read what Hillary Clinton said to her disappointed followers on June 7, 2008.

The primary season had ended four days earlier. She had virtually split the nationwide popular vote with Barack Obama, but she fatally trailed in the delegate count. Her delegate deficit was actually far smaller than Bernie's current deficit, but did she whine about "rigged" primaries? Nope. Did she have the gall to insist, as Bernie did on Monday, that her victorious foe surrender to her issue agenda? Nope. Here's a small sampling of what she said:

"The way to continue our fight now, to accomplish the goals for which we stand, is to take our energy, our passion, our strength, and do all we can to help elect Barack Obama, the next president of the United States. Today, as I suspend my campaign, I congratulate him on the victory he has won and the extraordinary race he has run. I endorse him and throw my full support behind him. And I ask all of you to join me in working as hard for Barack Obama as you have for me."

That's the way to do it. You face reality, and eat humble pie for the greater good.

The big question is not whether Bernie is toast — that's been obvious for weeks (he's losing the national popular vote by 57 to 43 percent, which in electoral parlance is known as a landslide). The real question is whether Bernie will stand down in a graceful manner. We're still six weeks away from the final contest, so there's time.

Right now, however, we're getting mixed signals. Tad Devine, a strategist in the Bernie camp, signaled the press early Tuesday that his candidate is prepared to "reassess." But on the same day the Bernie camp sought new donations by emailing a photo of the Clintons at Trump's wedding.

The candidate himself said Tuesday night he's proud of winning minuscule Rhode Island, "the one state with an open primary." He's stoked for "the 14 contests to come" and is vowing to fight at the July convention for the issue agenda that's losing decisively at the ballot box. (Here's what I mean by decisive: In the Pennsylvania exit polls, 52 percent said the nominee should "continue Obama's policies." Only 32 percent said the nominee should "change to more liberal policies.")

So we'll see which way Bernie plays it. As an outsider, a western European-style socialist who merely caucuses with the Democrats, he's comfortable with defiance. On TV the other night, he insisted that it's "incumbent" upon Hillary to make the first move toward winning over his fans. Which is quite cheeky, given the fact that she's the winner and he's the loser.

On the other hand, Bernie has been an inside-the Beltway politician for the past quarter century. If the Democrats win back the Senate this fall, presumably he would very much like to chair the Senate Budget Committee next year. Despite all his self-righteous thunder, he knows how to do deals. He hinted as much the other night, on MSNBC, when he said, "I will do everything in my power to make sure that no Republican gets into the White House in this election cycle."

If he wants to stay in the race through California, fine. And if he stops trashing Clinton on the stump, and hoses down Tim Robbins and his other celebrity dilettantes - that's when we'll truly begin to know whether he's doing everything in his power to kill the Trump poison before it fatally infects this country.

— Dick Polman is the national political columnist at NewsWorks/WHYY in Philadelphia and a "Writer in Residence" at the University of Pennsylvania. Email him at dickpolman7@gmail.com.